CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM SYSTEM DESCRIPTION


  1. SYSTEM DESCRIPTION


    1. The K312 Continuously Variable Transaxle is a fully electrohydraulically controlled steel belt type continuously variable transaxle. This is a highly efficient transaxle that is controlled in conjunction with the engine, contributing to enhanced fuel efficiency and quietness without shift shock. In addition, the continuously variable transaxle has the following features:


      • Diagnostic function

      • Fail-safe function when a malfunction occurs

  2. FUNCTION OF MAIN COMPONENTS


    1. The main components of the K312 CVT system are as follows:

      Component Outline
      Continuously Variable Transaxle Assembly Shift Solenoid Valve SC Used to switch control of the shift solenoid valve SLU between forward and reverse clutch control and lock-up clutch control.
      Shift Solenoid Valve SL
      Shift Solenoid Valve SLU Performs forward and reverse clutch control or lock-up clutch control depending on the state of the shift solenoid valves SC and SL.
      Shift Solenoid Valve SLP Controls the oil pressure of the primary pulley.
      Shift Solenoid Valve SLS Controls the oil pressure of the secondary pulley.
      Transmission Revolution Sensor (NIN) Detects the primary pulley speed.
      Transmission Revolution Sensor (NOUT) Detects the secondary pulley speed.
      Transmission Revolution Sensor (NT) Detects the input turbine speed.
      CVT Fluid Temperature Sensor Detects the CVT fluid temperature.
      Oil Pressure Sensor Detects the CVT oil pressure for belt clamping force.
      Stop Light Switch Assembly Detects the state of the brake pedal.
      Park/Neutral Position Switch Detects the position of the shift lever.
      Transmission Shift Switch Assembly (Shift Paddle Switch)

      • Detects the driver's shift-up and shift-down operations in 7-speed sport sequential shiftmatic mode.

      • Operating this switch when the shift lever is in D changes the mode temporarily to 7-speed sport sequential shiftmatic mode.
      Shift Lock Control Unit Assembly Transmission Control Switch

      • Detects that the shift lever is in M.

      • Detects the driver's shift-up and shift-down operations when the shift lever is in M.
      Combination Meter Assembly Shift Position Indicator Indicates the shift lever position.
      Malfunction Indicator Lamp (MIL) Illuminates or blinks to alert the driver that the ECM has detected a malfunction.
      ECM

      • Performs electronic control of the CVT system.

      • When the ECM detects a malfunction, it performs diagnosis and memorizes the malfunctioning area.
      Airbag ECU Assembly Yaw Rate Sensor Detects the vehicle's yaw rate.
      Acceleration Sensor Detects the vehicle's longitudinal and lateral acceleration and deceleration.
      Brake Actuator Assembly Skid Control ECU

      • Transmits the vehicle speed and the longitudinal acceleration signal to the ECM.

      • Transmits the operating states of the ABS and VSC to the ECM.
      Electric CVT Oil Pump (Oil Pump with Motor Assembly) Keeps CVT oil pressure at an adequate level while the stop and start system is operating.
      DLC3 Used for connecting the diagnosis tool to read diagnostic trouble codes and ECM data.

      Tech Tips

      The airbag ECU assembly incorporates the yaw rate sensor and acceleration sensor.

  3. OIL PUMP WITH MOTOR ASSEMBLY OPERATION CONTROL


    1. When the engine is stopped automatically by the stop and start system, the engine stop and start ECU operates the oil pump with motor assembly installed to the continuously variable transaxle to produce optimal CVT oil pressure for enhanced response of the continuously variable transaxle assembly and smooth start-off when the engine is automatically restarted.

      Tech Tips


      • Refer to the stop and start system operation conditions.

        Click here

      • The oil pump with motor assembly operates when the CVT oil temperature is between 25 to 111°C (77 to 232°F).

      • When the shift lever is in R, the engine will not be stopped by the stop and start system.

      Oil Pump with Motor Assembly Operation
      Shift Lever Position P R N D, S or B
      Brake Pedal Depressed Operates Does not operate Operates Operates
      Brake Pedal Released Operates Does not operate Operates Operates → Does not operate*

      • *: When the engine speed or vehicle speed reaches the threshold value, the oil pump with motor assembly will stop operating.